The present invention relates to a multiple density substrate for selective impact energy absorption, selective structural differences, selective durability, and a method of making the same in vehicles.
There is a growing need to improve the energy absorption properties of automotive interior trim substrates which also provide structural support to the sheet metal structure of a vehicle. Such sheet metal structures include pillars, side rails, and roof structures. However, the industry has been challenged in determining a cost effective way of manufacturing interior trim substrates and interior components in order to meet industry demands. For example, manufacturers continue to search for ways of improving the properties of substrates for absorbing energy in a cost effective manner while providing structural support.
One challenge that manufacturers are faced with is that energy absorption throughout the passenger compartment, such as on pillars, side rails, or the roof structure of a vehicle, requires different amounts or different densities of energy absorption material, including molded foam or beads. This is due to the vehicle structure design which typically includes a plurality of sheet metal pieces that form the passenger compartment of a vehicle. The thickness and geometric stiffness of the sheet metal typically determine the amount of energy absorption material required. That is, the thicker and/or stiffer the sheet metals is, the more absorption material is required to meet industry demands. Thus, materials of different amounts of energy absorption and/or different densities would be useful to have in interior trim substrates.
Although current energy absorbing parts may be adequate, improvements can be made thereupon. Currently, multi-density component parts are manufactured for energy absorbing purposes. Some multi-density component parts are separately manufactured and then combined to comprise an energy absorbing part which is fastened to an area of a vehicle compartment, such as a pillar. More specifically, single density foam or beads are molded to form a shape of a vehicle component. The molded foam or beads are then attached to a predetermined area on an interior trim material or a shell which then fastens onto the structure of a vehicle. The separate manufacturing processes used in forming the molded foam or beads and the interior trim substrates result in additional manufacturing time and costs.
U.S. Pat. No. 5,700,050 to Gonas discloses an energy absorbing interior automotive trim part. The part has a shell made from polypropylene sections is divided via partitions to extend from the outer wall of the shell. The shell is then filled with structurally engineered energy absorbing foam.
Thus, what is needed is an improved system and method of making an integrally formed substrate that more efficiently meets the industry demands for energy absorption on collision impacts.
An object of the present invention is to provide for an improved method of manufacturing a multiple density substrate for impact energy absorption with a mold having a mold cavity of a predetermined shape. The method includes providing a first set of unbonded beads of a first density and a second set of unbonded beads of a second density, loading the mold cavity with the first set of unbonded beads at a predetermined location in the mold cavity sufficiently to leave a void in the mold cavity, and separately injecting a sufficient amount of the second set of unbonded beads into the void. The method further includes bonding the first and second sets of beads together with heat to define a molded set of bonded beads having the predetermined shape, and cooling the molded set of bonded beads sufficiently to define the multiple density substrate.
Another object of the present invention is to provide an improved method of manufacturing a multiple density substrate for impact energy absorption with a mold of a predetermined shape. The method includes providing a bag containing a first set of unbonded pre-expanded beads of a first density and providing a second set of unbonded pre-expanded beads of a second density, loading a portion of the mold with the bag including the first set of unbonded beads at a predetermined location on the mold, and injecting the second set of unbonded beads into the mold. The method further includes bonding the first and second set of beads together with heat to define a molded set of bonded beads having the predetermined shape and cooling the molded set of bonded beads sufficiently to define the multiple density substrate.
Another object of the present invention is to provide an improved system for manufacturing a multiple density substrate for differential impact energy absorption with a mold of a predetermined shape, a first set of unbonded beads having a first density, and a second set of unbonded beads having a second density. The system includes a mechanism for loading a portion of the mold with the first set of unbonded beads at a predetermined location in the mold sufficiently to leave a void in the mold, and a mechanism for injecting the loaded mold portion with a sufficient amount of the second set of unbonded beads into the void. The system further includes a mechanism for bonding the first and second sets of beads together with steam to define a molded set of unbonded beads having the predetermined shape.
Yet another object of this invention is to provide for an improved multiple density substrate for impact energy absorption. The substrate is a molded set of bonded beads manufactured by a steam heating process and has a predetermined shape. The substrate comprises a first set of expanded bonded beads of a first density to define a first density level, a second set of expanded bonded beads of a second density integrally disposed adjacent the first set of expanded bonded beads, and a casing device of the first set of expanded bonded beads disposed between the first and second sets to sufficiently separate the first and second density levels to define the multiple density substrate of the predetermined shape.
An improved integrally formed substrate implementing a single method of manufacturing such substrate aids in reducing current manufacturing time and costs. Moreover, integrally formed, multiple density energy absorbing materials aid in improving the manufacture of interior substrates in meeting industry demands to absorb energy on collision impacts while providing adequate support.
Other objects, features, and advantages of the present invention will be apparent from the ensuing description in conjunction with the accompanying drawings.